Suggest Treatment For Stomach Pain, Bloating And Odd Stringy Looking Stool

I am 5 months pregnant and noticed awhile ago that my stool was looking odd. I have had brown thread like pieces in my poop which I thought could be worms so I was very concerned and had a stool sample done. The Dr tested me for pin worms and also parasites and ova I think it was which all came back negative... But today again I seen these thread like substances hanging off my poop. I am really worried if it is some sort of parasite that my baby will be harmed. I have also been bloated for the last few years with stomach pains and the dr figured it is my stomach lining or an ulcer And had me tAking stomach blockers for the acid but I am no longer on them since being pregnant ...